Cartridge fuse pull-out switch



April 23, 1968 H. H. DOWNS ET AL 3,379,842

CARTRIDGE FUSE PULL-OUT SWITCH Filed Sept. 23, 1964 3 $heets-$heet 1.

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CARTRIDGE FUSE PULL-OUT SWITCH Filed Sept. 23, 1964 5 Sheets-Sheet 4660 466 5 3506 I 336 5b as C) 4w 46 April 23, 1968 H. H. DOWNS ET AL CARTRIDGE FUSE PULL-OUT SWITCH Filed Sept. 23, 1964 United States Patent 3,379,842 CARTRIDGE FUSE PULL-OUT SWITCH-I Harold H. Downs and Harris I. Stanbaclr, Lexington, Ky., assignors to Square 1) Company, Park Ridge, Ill., a corporation of Michigan Filed Sept. 23, 1964, Ser. No. 398,637 Claims. (Cl. 200-114) This invention relates generally to fusible switch units, and more particularly to cartridge fuse pull-out switches adapted to be plugged into electrical panelboards.

An object of the invention is to provide a fusible switch unit including a casing having a line terminal adapted to be plugged on a bus bar of an electrical panelboard, and a pull-out type fuse holder removably insertable in the casing selectively in ON and OFF positions and adapted to hold a cartridge fuse in position to extend perpendicularly to a back wall portion of a box forming a part of the panelboard when the unit is connected to the bus bar with a fuse mounted therein.

Another object is to provide a fusible switch unit in eluding a casing and a pull-out type fuse holder removably insertable therein selectively in ON and OFF positions, the casing having two pairs of stationary contact jaws therein respectively adjacent opposite ends thereof and the fuse holder including a pair of combination fuse clip and plug-in terminal jaw members the fuse clip portions of which are respectively adapted to hold opposite end portions of a. cartridge fuse and the terminal jaw portions of which extend in opposite directions from their respective fuse clip portions radially from a cartridge fuse held therein for engagement respectively with the pairs of stationary contact jaws in the ON position of the fuse holder.

Still another object is to provide such a fusible switch unit wherein the terminal jaw portions of one of the combination fuse clip and terminal jaw members are spaced axially of a ferrule of a cartridge fuse :held in the respective fuse clip portion and a pair of inwardly bent tongue portions are provided on the one combination fuse clip and terminal jaw member to maintain proper gripping pressure between the fuse ferrule and the respective fuse clip portion when the respective terminal jaw portions are inserted between the respective pair of stationary contact jaws in the ON position of the fuse holder.

A further object is to provide a fusible switch unit including a casing and a pull-out type fuse holder removably insertable therein selectively in ON and OFF positions, the casing having two pairs of stationary contact jaws therein respectively adjacent opposite ends thereof, the fuse holder including two pairs of oppositely extending plug-in type terminal jaw portions respectively engageable with the stationary contact jaws in the ON position of the fuse holder, and the stationary contact jaws of one pair being spaced more widely apart than those of the other pair so that one pair of the terminal jaw portions of the fuse holder may pass freely therethrough when the fuse holder is inserted in the casing in the OFF position thereof.

Yet another object is to provide such a fusible switch unit wherein the casing includes portions spaced substantially the same distance apart as the jaws of one pair of stationary contact jaws and receiving and gripping one pair of the terminal jaw portions of the fuse holder in the OFF position thereof.

A still further object is to provide a fusible switch unit adapted to be plugged into an electrical panelboard and including a casing, 21 pull-out type fuse holder therein. and two pairs of stationary contact jaws therein, one pair being formed integrally with a pair of plug-in type line terminal jaws and the other pair being formed integrally with a load terminal for receiving a load wire.

An additional object is to provide a fusible switch unit 3,379,842 Patented Apr. 23, 1958 including a casing, a pull-out type fuse holder removably insertable in the casing selectively in ON and OFF positions, an indicating lamp in the casing, and a pair of combination fuse clip and plug-in terminal jaw members secured to the fuse holder respectively by a pair of fastening means, the circuit through the indicating lamp being completed in the ON position of the fuse holder through the fastening means for the combination fuse clip and terminal jaw members.

A still additional object is to provide a fusible switch unit including a casing having a pair of line terminal jaws extending outwardly thereof and adapted to be plugged on a bus bar of an electrical panelboard, a pull-out type fuse holder removably insertable in the casing selectively in ON and OFF positions, and means on the terminal jaws preventing the fusible unit from being pulled away from the bus bar when the fuse holder is pulled out of the easing.

Other objects will appear when the following specification is considered along with the accompanying drawings in which:

FIG. 1 is a side elevations-.1 view of a two-pole fusible switch unit constructed in accordance with the invention;

FIG. 2 is an end elevational view of the fusible switch unit of FIG. 1;

FIG. 3 is a top plan View of the fusible switch unit of FIG. 1, the fuse holder being shown in ON position and the handle for the fuse holder having been rotated to a flush position;

FIG. 4 is a fragmentary sectional view of the fusible switch unit of FIG. 1 taken generally along the line 44 of FIG. 8;

FIG. 5 is an enlarged perspective view of one of the combination load terminal and stationary contact jaw assemblies of the fusible switch unit of FIG. 1;

FIG. 6 is an enlarged perspective view of one of the combination line terminal and stationary contact jaw assemblies of the fusible switch unit of FIG. 1;

FIG. 7 is a sectional view of the fusible switch unit of FIG. 1 taken generally along the line 77 of FIG. 8;

FIG. 8 is an enlarged view similar to FIG. 1, but with a portion of the casing removed, the fuse holder being shown in ON position;

FIG. 9 is an enlarged end elevational view of the fuse holder of the fusible switch unit of FIG. 1, looking at the line end thereof;

FIG. 10 is an enlarged side elevational view of the fuse holder of the fusible switch unit of FIG. 1; and

FIG. 11 is an enlarged end elevational view of the fuse holder of the fusible switch unit of FIG. 1, looking at the load end thereof.

FIGS. 1-3 show a two-pole fusible switch unit 20 constructed in accordance with the invention and including a casing 22 and a fuse holder 24 removably insertable therein selectively in ON and OFF positions. Preferably the casing 22 is molded of electrically insulating material and in three parts 22a, 22b and 22c held together preferably by a plurality of rivets 26. The casing part 22a and the portion of the casing part 22c adjacent thereto form a housing, including side wall portions, for a first pole of the two-pole fusible switch unit 20, and the casing part 22b and the portion of the casing part 220 adjacent thereto form a housing, including side wall portions, for a second pole of the two-pole fusible switch unit 20. The casing parts 22a, 22b, and 220 are formed to provide a bottom wall portion 22d (FIG. 8).

Near the bottom and adjacent one end of the casing 22, each pole of the two-pole fusible switch unit 20 is provided with a plug-in line terminal and stationary contact jaw assembly 28 best shown in FIG. 6 and preferably constructed of two symmetrical electrically conductive members 28a and 28b secured together by a pair of rivets 29 and formed to provide a pair of spaced plug-in terminal jaws 28c and 28d adjacent one end and a pair of spaced stationary contact jaws 28a and 28 adjacent the other end. The sets of jaws 28c and 28d of the two poles are respectively adapted to plug on a pair of bus bars of an electrical panelboard (not shown). Preferably, means are provided to prevent the fusible switch unit from being pulled away from the bus bars of an electrical panelboard as the fuse holder 24 is pulled from the casing 22. Such means may take the form of a pair of detents 28g formed respectively on the jaws 28d of the two poles.

Near the bottom and adjacent the other end of the casing 22, each pole is provided with a mounting clip 30 adapted to plug on a mounting rail of an electrical panelboard (not shown). Above the mounting clips 30 adjacent the same end of the casing 22, each pole is provided with a load terminal and stationary contact jaw assembly 32 best shown in FIG. 5 and preferably constructed of a clamping screw 33 and a one-piece electrically conductive member 32a formed to provide a pair of spaced stationary contact jaws 32b and 320 adjacent one end and a generally rectangular load terminal body portion 32d adjacent the other end threadedly receiving the screw 33. A pair of generally aligned apertures 32a and 32 are provided in opposite wall portion of each body portion 32d for the reception of a load wire and clamping thereof by the respective screw 33.

As best shown in FIG. 8, each pole is also provided with an indicating lamp 34 having a pair of lead wires 35 and 36 electrically connected respectively to a pair of resilient stationary contact members 37 and 33, the lead wire 35 being connected to the stationary contact I ember 37 through a resistor 40. The casing parts 22a, 22b, and 22c are provided respectively with appropriate recesses and projections for trapping the mounting clips 30, the assemblies 28 and 32, the indicating lamps 34, the stationary contact members 37 and 38, and the resistors 49 in proper position in the casing 22.

The fuse holder 24 is shown best in FIGS. 9, l0, and 11 and includes a frame 42 preferably molded of insulating material, a wire handle 44 pivotally mounted on the frame 42, a pair of combination fuse clip and plug-in terminal jaw members 46 secured to the frame 42 respectively by a pair of screws 48 provided with lock washers 50 and adapted to plug into the stationary contact jaws 32b and 320 of the load terminal in the ON position of the fuse holder 24, and a pair of combination fuse clip and plug-in terminal jaw members 52 secured to the frame 42 respectively by another pair of screws 48 provided with lock washers 50 and adapted to plug into the stationary contact jaws 28a and 28 of the line terminal in the ON position of the fuse holder 24.

The frame 42 includes a pair of depending leg portions 42a each of which has one of the combination fuse clip and terminal jaw members 46 and one of the combination fuse clip and terminal jaw members 52 mounted thereon. Each leg portion 42a is provided with a reinforcing web portion 42b adjacent the other leg portion 42a, the web portions 42b being spaced apart as shown in FIG. 11 so that a central narrow outer portion 226 (FIG. 7) of the casing part 220 may be received therebetween.

Each of the combination fuse clip and terminal jaw members 46 includes a flat portion 46a provided with an extruded hole into which the respective screw 48 is threaded to fasten the member 46 to the respective leg portion 42a, a pair of opposed generally cylindrical fuse clip portions 46b, a pair of opposed terminal jaw portions 460 respectively extending from the fuse clip portions 46b in a direction away from the respective leg portion 42a, and a pair of inwardly bent tongue portions 46d provided for a purpose hereinafter set forth. The terminal jaw portions 460 are appropriately tapered for easy insertion between the respective stationary contact jaws 32b and 32c.

Each of the combination fuse clip and terminal jaw members 52 includes a flat portion 52a provided with an extruded hole into which the respective screw 48 is threaded to fasten the member 52 to the respective leg portion 42a, a generally cylindrical fuse clip portion 52b, and a pair of opposed terminal jaw portions 520 respectively extending from the fuse clip portion 5212 back toward the respective leg portion 42a in an opposite direction from the direction in which the terminal jaw portions 460 extend from the fuse clip portions 46b. The terminal jaw portions 520 are appropriately tapered for easy insertion between the respective stationary contact jaws 28c and 28f.

The fuse holder 24 is adapted to be received in the casing 22 selectively in ON and OFF positions, the easing part 22a being provided with a suitable ON indicium as shown in FIG. 3, the casing part 22b being provided with a suitable OFF indicium, and the frame 42 of the fuse holder 24 being marked, as at 54, to indicate in which of the ON and OFF positions the fuse holder 24 is disposed in the casing 22.

As shown in FIGS. 4, 7, and 8, the fuse holder 24 is adapted to hold a pair of cartridge fuses 56 in the respective fuse clip portions 46b and 5212, which are appropriately tapered for easy reception of the fuses axially thereof. It will be noted from FIG. 8 that installed fuses 56 extend perpendicularly to the bottom wall portion 22d of the casing 22 from which the mounting clips 30 and the line terminal jaws 28c and 28d extend and are moved axially when the fuse holder 24 is inserted in or removed from the casing 22.

The extension of the terminal jaw portions 52c from the fuse clip portions 52b in an opposite direction from the direction in which the terminal jaw portions 460 extend from the fuse clip portions 46b results in short cur-rent paths from the terminal jaw portions 520 and 46c respectively to the line terminal jaws 28c and 28d and to the load terminal body portion 32d, and therefore in less heat when the fusible unit is in use, and in lower manufacturing costs.

The load stationary contact jaws 32b and 32c are spaced more widely apart from each other than the line stationary contact jaws 28a and 287, as can be seen from a comparison of FIGS. 4 and 7. Therefore, when the fuse holder 24 is inserted in the casing 22 in the OFF position, the terminal jaw portions 52c will pass readily through the stationary contact jaws 32b and 32a.

Toward the bottom of the casing 22 and to the right of the fuses 56 as viewed in FIG. 4, the casing parts 2 2a and 220 are thickened so that the distance therebetween is substantially the same as the distance between the stationary contact jaws 28e and 25) of the first pole, and the casing parts 22b and 220 are thickened so that the distance therebetween is substantially the same as the distance between the stationary contact jaws 28e and 28f of the second pole. Therefore, when the fuse holder 24 is inserted in the casing 22 in the OFF position, it will be retained therein by engagement of the sets of terminal jaw portions 520 respectively, with the casing parts 22a and 220 and with the casing parts 22b and 220.

As can be seen in FIG. 8, the stationary contact jaws 32b and 320 of each pole are spaced axially of the upper ferrule or end cap: of the respective fuse 5'6, and the squeezing of the terminal jaw portions 46c between the stationary contact jaws 32b and 320 tends to decrease the gripping pressure between the fuse clip portions 46b and the upper ferrule of the respective fuse 56. In order to insure that enough gripping pressure for a good electrical connection between the fuse clip portions 46b and the respective fuse 56 is maintained, the inwardly bent ton'g'ue portions 46d are provided to prevent the respective terminal jaw portions 460 from being squeezed so close together as to decrease the gripping pressure on the upper ferrule of respective fuse 56 too much.

As can be seen in FIG. 8, in the ON position of the fuse holder 24, the circuit through the indicating lamp 3 4 of each pole is completed by engagement of the respective resilient stationary contact members 37 and 38 with the respective screws 48 which hold the combination fuse clip and terminal jaw members 46 and 52 to the respective leg portions 42a of the frame 42. When the circuits through the two poles are energized by the plugging of the fusible switch unit into an electrical p'anelboard with the fuse holder 24 in the ON position, not enough current normally flows through the indicating lamps 34 to make them glow, because the electrical resistance of the circuits including the resistors 40 and the indicating lamps 34 is high relative to that of the fuses 56. However, if a fuse 56 is blown or absent, current will flow through the respective indicating lamp 34 and make it glow.

Terms used herein having directional connotations are purely relative, it being understood that the fusible switch unit 20 may be mounted in various positions.

Various modifications may be made in the structure disclosed without departing from the spirit and scope of the invention as set forth in the claims appended hereto.

We claim:

)1. A cartridge fuse pull-out switch comprising a casing formed of electrically insulating material and having a bottom wall portion, a first pair of stationary contact jaws in said casing adjacent one end thereof and adjacent said bottom wall portion, a second pair of stationary contact jaws in said casing adjacent the other end thereof and remote from said bottom wall portion, and a fuse holder removably insertable in said casing selectively in ON and O FF positions with respect thereto, said fuse holder having first and second oppositely extending plug-in terminal portions respectively engageable with said first and second pairs of stationary contact jaws in the ON position of said fuse holder, and the jaws of said second pair of stationary contact jaws being more widely spaced apart from each other than the jaws of said first pair, whereby said first terminal portion of said fuse holder passes relatively freely bet-ween the jaws of said second pair when said fuse holder is being inserted in said casing in the OFF position thereof.

2. A cartridge fuse pull-out switch comprising a casing formed of electrically insulating material and having a bottom wall portion and a pair of opposed side wall portions, a first pair of stationary contact jaws in said casing adjacent one end thereof and adjacent said bottom wall portion, a second pair of stationary contact jaws in said casing adjacent the other end thereof and remote from said bottom wall portion, and a fuse holder removably insertable in said casing selectively in ON and OFF positions with respect thereto, said fuse holder having first and second oppositely extending plug-in terminal portions respectively engageable with said first and second pairs of stationary contact jaws in the ON position of said fuse holder, the jaws of said second pair of stationary contact jaws being more widely spaced apart from each other than the jaws of said first pair, whereby said first terminal portion of said fuse holder passes relatively freely between the jaws of said second pair when said fuse holder is being inserted in said casing in the OFF position thereof, and said side wall portions adjacent said bottom wall portion and adjacent said other end of said casing being spaced apart from each other substantially the same distance as the jaws of said first pair of stationary contact jaws are spaced apart from each other, whereby said fuse holder is retained in said casing in the OFF position thereof by frictional engagement solely between said first terminal portion and said side wall portions adjacent said bottom wall portion and adjacent said other end of said casing.

3. A cartridge fuse pull-out switch comprising a casing having a bottom wall portion and a plug-in line terminal and stationary contact jaw assembly, said assembly including two symmetrical electrically conductive members secured together and formed to provide a pair of spaced stationary contact jaws in said casing and to provide a pair of spaced plug-in line terminal jaws extending outwardly of said casing through said bottom wall portion, each of said members including one of said stationary contact jaws and one of said plug-in line terminal jaws.

4. A cartridge fuse pull-out switch comprising a casing, a pair of stationary contact jaws in said casing, a fuse holder removably insertable in said casing selectively in ON and OFF positions with respect thereto, said fuse holder including a combination fuse clip and terminal jaw member having a fuse clip portion and a pair of ter minal jaw portions, a cartridge fuse having a ferrule disposed in said fuse clip portion, said terminal jaw portions being disposed between said stationary contact jaws and said stationary contact jaws being displaced from said ferrule in a direction parallel to the axis of said fuse when said fuse holder is in ON position in said casing, and means on said member preventing said terminal jaw portions from being squeezed so closely together by said stationary contact jaws as to relieve the clamping pressure of said fuse clip portion on said ferrule sufficiently to result in a poor electrical connection therebetween.

5. A cartridge fuse pull-out switch comprising a casing, an indicating lamp in said casing, said indicating lamp having a pair of lead wires energizable to make said lamp glow, a pair of resilient stationary contact members in said casing respectively electrically connected to said lead wires, two pairs of stationary contact jaws in said casing, and a fuse holder removably insert-able in said casing selectively in ON and OFF positions with respect thereto, said fuse holder including a frame formed of electrically insulating material, a pair of combination fuse clip and terminal jaw members each having a fuse clip portion and a pair of terminal jaw portions, and a pair of fastening means respectively securing said members to said frame, the pairs of terminal jaw portions of said members being engaged respectively with said pairs of stationary contact jaws and said fastening means being electrically connected respectively to said resilient stationary contact members when said fuse holder is in the ON position in said casing.

FOREIGN PATENTS 6/ 1928 Australia. 11/ 1928 Switzerland.

a BERNARD A. GILHEANY, Primary Examiner.

GEORGE HARRIS, Examiner.

H. A. LEWITTER, Assistant Examiner. 

1. A CARTRIDGE FUSE PULL-OUT SWITCH COMPRISING A CASING FORMED OF ELECTRICALLY INSULATING MATERIAL AND HAVING A BOTTOM WALL PORTION, A FIRST PAIR OF STATIONARY CONTACT JAWS IN SAID CASING ADJACENT ONE END THEREOF AND ADJACENT SAID BOTTOM WALL PORTION, A SECOND PAIR OF STATIONARY CONTACT JAWS IN SAID CASING ADJACENT THE OTHER END THEREOF AND REMOTE FROM SAID BOTTOM WALL PORTION, AND A FUSE HOLDER REMOVABLY INSERTABLE IN SAID CASING SELECTIVELY IN ON AND OFF POSITIONS WITH RESPECT THERETO, SAID FUSE HOLDER HAVING FIRST AND SECOND OPPOSITELY EXTENDING PLUG-IN TERMINAL PORTIONS RESPECTIVELY ENGAGEABLE WITH SAID FIRST 